Theory and models of pedestrian crossing behaviour along urban trips

The objective of this research is to develop and test a theoretical framework for modelling pedestrian crossing behaviour along trips in urban areas. The general question examined concerns the estimation of the probability to cross at each alternative location within a pedestrian's crossing choice set, associated with each crossing decision made along an urban trip. A topological consideration of urban road networks and pedestrian trips is opted for, which enables the overall parameterisation of the problem and the estimation of the number and type of crossings along a pedestrian trip. On the basis of certain topological properties of pedestrian trips, an algorithm is then developed for determining the set of choice alternatives for each crossing along the trip. Finally, specific techniques from the family of discrete choice models are proposed for modelling the choice of a crossing location from the available alternatives in each case. Different hypotheses are examined with respect to road crossing decision making process (sequential or hierarchical decision making) and various models are tested in each case (multinomial, nested, or cross-nested models). For the development of the proposed models, a field survey is carried out, in order to collect detailed data on pedestrian trips and crossings in urban areas per road network, traffic conditions and pedestrian characteristics. The modelling results reveal increased probability of crossing at the beginning of the trip, a tendency to postpone crossings in longer trips, especially for pedestrians with increased walking speeds, increased probability of crossing at signalised junctions, when available, and increased probability of crossing at mid-block in low traffic volumes and on one-way roads. Moreover, the hypothesis of sequential decision making is proved to be more promising for the description of pedestrians' crossing choices along urban trips.